Integrally bladed rotor assemblies are used in the compressor and turbine sections of a gas turbine engine. These assemblies can be fabricated or repaired by joining separately formed blades to a disc or ring.
Friction welding is one of the techniques that can be used to join the blades to the disc or ring. In friction welding either one or both of the blade and disc are moved relative to one another whilst being urged together with sufficient force to generate frictional heating. A multiplicity of blades are joined to the disc in this way.
The blades are friction welded to stubs of material upstanding from the periphery of the disc. The geometry of the stubs is however such that it has insufficient stiffness for the welding process.